Mechanism for closing a lid

A mechanism for controlling the opening and closing of a closure object comprising:

• an outer cylinder having therein an inner chamber, said inner chamber having contained therein hydraulic fluid, and a distal end of said outer cylinder being attachable to one of the group consisting of a closure object and an object to be closed;
• a circumferential single groove located in an inner wall of said outer cylinder;
• a piston shaft telescopically received within said outer cylinder, said piston shaft extending proximally out of the outer cylinder and attachable to the other one of a group consisting of a closure object and an object to be closed, said piston shaft extending distally into said inner chamber;
• a piston head mounted distally on said piston shaft, said piston head and an inner wall of said outer cylinder defining a distal chamber and a proximal chamber, said piston head containing a bore therethrough, a peripherally located circumferential retaining groove, and an inclined outer surface increasing in cross section and having a minimal cross section proximally;
• sealing means for preventing hydraulic fluid from passing around said piston head between said distal chamber and said proximal chamber;
• a snap ring partially housed within said single groove and being engageable with said inclined outer surface of said piston head;
• a retainer mounted proximate the distal end of said piston shaft;
• and
• a valve plate, slideably mounted on said piston shaft between said retainer and said piston head, said valve plate having an orifice extending therethrough.